* Fix floating 'latest' tag logic: dereference annotated target (vX.Y.Z^{}), add tag message to avoid Git errors, ensure best-effort update without blocking releases, and update unit tests (see ChatGPT conversation: https://chatgpt.com/share/69383024-efa4-800f-a875-129b81fa40ff).
* Add Git helpers for branch sync and floating 'latest' tag in the release workflow, ensure main/master are updated from origin before tagging, and extend unit/e2e tests including 'pkgmgr release --help' coverage (see ChatGPT conversation: https://chatgpt.com/share/69383024-efa4-800f-a875-129b81fa40ff)
* Expose DISTROS and BASE_IMAGE_* variables as exported Makefile environment variables so all build and test commands can consume them dynamically. By exporting these values, every Make target (e.g., build, build-no-cache, build-missing, test-container, test-unit, test-e2e) and every delegated script in scripts/build/ and scripts/test/ now receives a consistent view of the supported distributions and their base container images. This change removes duplicated definitions across scripts, ensures reproducible builds, and allows build tooling to react automatically when new distros or base images are added to the Makefile.
* Refine pkgmgr release CLI close wiring and integration tests for --close flag (ChatGPT: https://chatgpt.com/share/69376b4e-8440-800f-9d06-535ec1d7a40e)
* Add pkgmgr branch close subcommand, extend CLI parser wiring, and add unit tests for branch handling and version version-selection logic (see ChatGPT conversation: https://chatgpt.com/share/693762a3-9ea8-800f-a640-bc78170953d1)
* Add branch closing helper and --close flag to release command, including CLI wiring and tests (see https://chatgpt.com/share/69374aec-74ec-800f-bde3-5d91dfdb9b91)
* Add preview-first release workflow and extended packaging support (see ChatGPT conversation: https://chatgpt.com/share/693722b4-af9c-800f-bccc-8a4036e99630)
* Implement unified release helper with preview mode, multi-packaging version bumps, and new integration/unit tests (see ChatGPT conversation 2025-12-08: https://chatgpt.com/share/693722b4-af9c-800f-bccc-8a4036e99630)